グカネータ / 質問パターン見直し (#41) (#365)

Reviewed-on: #365
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

backend/app/controllers/gekanator_games_controller.rb

@@ -27,26 +27,20 @@ class GekanatorGamesController < ApplicationController
     game = GekanatorGame.find_by(id: params[:id])
     return head :not_found unless game
 
-    asked_ids = Array(game.answers).filter_map { |answer| answer_question_id(answer) }
-    existing_example_ids =
-        GekanatorQuestionExample.where(post_id: game.correct_post_id)
-                                .select(:gekanator_question_id)
-    # Direct examples only for now; post_similarity-based expansion is deferred.
     questions =
         GekanatorQuestion
         .accepted
+        .includes(:gekanator_question_examples)
         .where(kind: 'post_similarity', source: 'user_suggested')
-        .where.not(id: existing_example_ids)
-        .order(priority_weight: :desc, id: :asc)
+        .to_a
+
+    selected = weighted_sample_questions(
+        questions,
+        post_id: game.correct_post_id,
+        limit: 2)
 
     render json: {
-      questions: questions.filter_map { |question|
-        json = extra_question_json(question)
-        next if asked_ids.include?(json[:id].to_s)
-        next if asked_ids.include?("post-similarity:#{ json[:id] }")
-
-        json
-      }.first(2)
+      questions: selected.map { |question| extra_question_json(question) }
     }
   end
 
@@ -84,11 +78,10 @@ class GekanatorGamesController < ApplicationController
                 gekanator_question: question,
                 post: game.correct_post,
                 user: current_user)
-        example.assign_attributes(
-            gekanator_game: game,
+        example.record_answer!(
             answer: item[:answer],
             source: 'post_game_extra',
-            weight: 1.0)
+            gekanator_game: game)
         example.save!
       end
     end
@@ -107,12 +100,41 @@ class GekanatorGamesController < ApplicationController
     }
   end
 
-  def answer_question_id answer
-    value = if answer.is_a?(Hash)
-      answer['question_id'].presence || answer[:question_id].presence ||
-        answer['questionId'].presence || answer[:questionId].presence
+  def weighted_sample_questions questions, post_id:, limit:
+    remaining = questions.uniq(&:id)
+    selected = []
+
+    while selected.length < limit && remaining.any?
+      weighted =
+          remaining.map { |question|
+            [question, selection_weight_for(question, post_id: post_id)]
+          }
+      total_weight = weighted.sum { |_question, weight| weight }
+      break if total_weight <= 0
+
+      target = rand * total_weight
+      cumulative = 0.0
+      chosen =
+          weighted.find do |_question, weight|
+            cumulative += weight
+            cumulative >= target
+          end&.first || weighted.first.first
+
+      selected << chosen
+      remaining.reject! { |question| question.id == chosen.id }
     end
 
-    value&.to_s
+    selected
+  end
+
+  def selection_weight_for question, post_id:
+    sample_count =
+        question.gekanator_question_examples.sum { |example|
+          next 0 unless example.post_id == post_id
+
+          example.sample_count.presence || 1
+        }
+
+    question.priority_weight.to_f / (1.0 + sample_count * 0.15)
   end
 end